JP2011012318A - Magnesium alloy member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnesium alloy member whose surface is provided with an active modified layer, and which has excellent adhesive properties and coating properties.SOLUTION: Disclosed is the magnesium alloy member consisting of an Al-containing magnesium alloy, wherein the modified layer containing Al having higher content than that of any unmodified base portion of the magnesium alloy is formed at a surface thereof. The magnesium alloy member is adhered to the other member through such a modified layer, and a coating film is formed.

Description

  TECHNICAL FIELD The present invention relates to a magnesium alloy surface modification technique and a bonding and coating technique using the same, and relates to a magnesium alloy member having a modified layer that activates the surface of the magnesium alloy and has excellent adhesion. . The present invention also relates to a magnesium alloy member bonded to another member via the modified layer, and further to a magnesium alloy member provided with a coating layer via the modified layer.

  In recent years, for the purpose of reducing the weight of vehicles, applications of light metal materials mainly composed of aluminum, magnesium, and the like have been expanded along with resin materials such as polyethylene and polypropylene.

  The development of the technology to bond these light metal materials or between light metal materials and other materials and integrate them is supported by the surface modification of the light metal material as the adherend and the technological development of adhesives. Of these, surface modification of the light metal material that is the adherend, that is, a treatment method before bonding, is a surface treatment method using a chromium-free acidic composition, for example, after treatment with an aqueous solution of a component that can be a film having excellent corrosion resistance, A surface treatment method for fixing a film by baking and drying without washing with water has been proposed (see Patent Document 1).

JP-A-5-195244

However, since the method described in Patent Document 1 does not involve a chemical reaction in the formation of a film, it cannot be applied to various metal materials such as magnesium alloys as well as iron, steel, zinc alloys, and aluminum alloys. is there.
However, since a surface treatment film is formed by treatment and drying, it is difficult to uniformly treat complicated structures such as vehicle members. Especially, magnesium alloy has a treatment film with excellent durability. There was a problem that it was difficult to obtain adhesiveness.

  The present invention has been made in view of the above-mentioned problems in conventional surface treatment methods and surface modification techniques relating to light metal materials, particularly magnesium alloys. The object of the present invention is to provide an active modified layer on the surface. Provided is to provide a magnesium alloy member having excellent adhesion.

  As a result of repeating earnest studies to solve the above problems, the present inventors form a modified layer containing Al higher than the original part of the member on the surface of the magnesium alloy member containing Al. Thus, the inventors have found that the above object can be achieved, and have completed the present invention.

  That is, the magnesium alloy member of the present invention is based on the above knowledge and is composed of a magnesium alloy containing Al, and has a modified layer on the surface thereof, and Al content on the surface of the modified layer. The amount is higher than that of the original part.

  According to the present invention, the surface of a member made of a magnesium alloy containing Al is provided with a modified layer, and the Al content on the surface is higher than that of the original part. This can improve the adhesion of the magnesium alloy member.

It is the schematic which shows the shape and dimension of the magnesium alloy member used for adhesive evaluation in the Example of this invention. It is the schematic which shows the shape and dimension of the adhesion test piece used for the adhesive evaluation in the Example of this invention.

  Hereinafter, the magnesium alloy member of the present invention will be described more specifically and in detail along with the production method thereof. In the present specification, “%” means mass percentage unless otherwise specified.

As described above, the magnesium alloy member of the present invention has a modified layer on the surface thereof, and the Al content on the surface of the modified layer is higher than that of the primary part.
That is, since the surface of the modified layer is enriched with Al, the content of Mg is relatively reduced, and the hard-to-adhere magnesium oxide is reduced. Covalent bonds and hydrogen bonds with Al are easily formed, and adhesion and paintability are improved.

  The Al content in the magnesium alloy member of the present invention is not necessarily limited as long as Al is contained, but is preferably a magnesium alloy containing 2% or more of Al, and is a modified layer rich in surface activity. Can be more reliably formed.

Specific examples of such alloy materials include Al-containing magnesium alloys such as AZ31, AZ31B, AZ61, AZ91, AZ91D, AM50, AM60, and AM60B defined in SAE (American Automotive Engineering Standard) J465. it can.
Here, the notations “AZ” and “AM” represent added metal elements, “A” is aluminum, “M” is manganese, and “Z” is zinc. The numbers following these notations indicate the addition ratio of these additive elements. For example, in the case of AZ91, aluminum is 9% and zinc is 1%. Among these magnesium alloys, AZ31, AZ61, AZ91, AM60, and AM60B can be given as representative examples.

  Other specific examples include AS21X (trade name of a magnesium alloy plate containing 2% Al and 1% Si), MRI153 (product of a magnesium alloy plate containing 8% Al and 1% Ca). It is also possible to use a magnesium alloy plate such as

The method for producing the main body portion of the magnesium alloy member of the present invention is not particularly limited, and for example, a material obtained by a molding method such as casting using a mold or sand mold (including die casting), extrusion, forging, or pressing can be used. .
In addition, the modified layer is not necessarily applied to the entire surface of the alloy member, and can be locally applied only to a portion that needs to be processed, for example, a portion to be bonded or painted.

  About the Al content on the surface of the modified layer, it is desirable that the Al content in the main body part of the magnesium alloy member, that is, the primary part of the alloy base material is enriched to 1.5 times or more. Excellent adhesion and paintability (cohesion of paint) will be exhibited.

  The method for producing the magnesium alloy member of the present invention, that is, the method for forming the modified layer enriched with Al on the surface of the magnesium alloy substrate is not particularly limited. Steam treatment that exposes to water vapor can be applied. In this case, since Mg on the surface of the magnesium alloy elutes, magnesium oxide on the surface disappears, and Al present in the magnesium alloy is exposed, so that Al is enriched. In addition to steam treatment, Al on the surface of the magnesium alloy can be enriched by Al plating, ion implantation, or the like.

On the other hand, it is preferable to employ an immersion treatment in which the magnesium alloy base material is immersed in an aqueous solution containing at least one inorganic chloride.
The treatment liquid used for the immersion treatment is preferably a metal chloride among inorganic chlorides, for example, lithium chloride, rubidium chloride, potassium chloride, barium chloride, strontium chloride, calcium chloride, sodium chloride, magnesium chloride, etc. Alternatively, various aqueous solutions are used in combination. In this case, the chlorine concentration in the aqueous solution is preferably 0.004 mol% or more to the saturation concentration or less.

  Such inorganic chlorides, especially metal chlorides, are simply dissociated (ionized) into chlorine ions and metal ions (cations) in water, and are highly soluble in water, thus increasing the concentration of OH ions in an aqueous solution. . Therefore, the generation of double hydroxides on the surface of the magnesium alloy material as will be described later is also efficient.

By immersing the magnesium alloy in such a chloride aqueous solution, the Mg element on the alloy surface is preferentially eluted, and the Al element in the alloy can be exposed and concentrated on the surface. A highly reliable modified layer can be efficiently formed without causing a reduction in the strength of the material and a deterioration in the durability of the surface modified layer.
That is, on the surface of the magnesium alloy, due to the elution of Mg, the content of magnesium oxide, which is a difficult adhesion component, decreases, and the content of Al element relatively increases. As a result, functional groups such as acrylic groups, epoxy groups, isocyanate groups, and hydroxyl groups contained in adhesive resins and component resins of paints easily form chemical bonds such as covalent bonds and hydrogen bonds. And paintability (cohesiveness of paint) will be exhibited.

  In the present invention, as a method for confirming that Al is exposed on the surface of the magnesium alloy member and Al is concentrated, for example, an X-ray photoelectron spectroscopy (XPS) method can be cited. By obtaining the element content (mol%) based on this method, it can be easily confirmed.

It is desirable that a double hydroxide containing Al and Mg is formed on the surface of the modified layer in the magnesium alloy member of the present invention. Such a double hydroxide can be formed by, for example, the above-described immersion treatment, and can also be generated as a precipitate by mixing a divalent and trivalent mixed metal salt aqueous solution with an alkaline solution. .
The double hydroxide can be represented by, for example, Mg _8-x Al _2x CO ₂ .nH ₂ O (x = 2, 3, 4, 5, n = 0, 1, 2, 3,...). It has the property of easily forming a chemical bond such as a covalent bond or a hydrogen bond with a functional group such as an acrylic group, an epoxy group, an isocyanate group or a hydroxyl group contained in the resin component of the adhesive or paint. In addition, the adhesiveness and durability of the adhesive and paint are greatly improved by the adhesion of crystal water and adsorbed water contained in the double hydroxide. Note that C in the above chemical formula is derived from the reaction of carbon dioxide and Mg in the air to produce magnesium carbonate.

  In order to confirm that the double hydroxide as described above is formed in the modified layer of the magnesium alloy member, for example, the spectrum observed by Fourier transform infrared spectroscopic analysis (FT-IR) is used. This can be done by analyzing.

The magnesium alloy member of the present invention can be a joined body joined to another member via an adhesive resin layer on the surface of the modified layer having an Al content higher than that of the original part.
Here, there is no limitation as to other members, that is, mating members, and members and articles made of various materials can be applied. Of course, using the magnesium alloy member of the present invention having a modified layer as a counterpart material, that is, joining the magnesium alloy members of the present invention together is also included.

  Specific examples of the mating member include, for example, polyolefin resins including polyethylene (PE) resin and polypropylene (PP) resin, polystyrene (PS) resin, polyvinyl chloride (PVC) resin, polyester resin, polyamide (PA) resin, Polyamideimide (PAI) resin, acrylonitrile butadiene styrene (ABS) resin, polycarbonate (PC) resin, polyacetal (POM) resin, acrylic resin, urea resin, melamine resin, epoxy resin, phenol (PF) resin, polyphenylene sulfide ( Plastic molded products made of PPS resin, etc., metal molded products made of steel materials, aluminum alloys, magnesium alloys, copper alloys, titanium alloys, woven fabrics made of carbon fibers, aramid fibers, glass fibers, natural fibers, natural rubber, etc. The sti Down-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), ethylene propylene rubber (EPDM) rubber molded article and the like, and the like glass and ceramic products. Among these members, resin molded products and metal molded products are preferable.

In addition, as the above-mentioned adhesive resin layer, it is applied to at least a part of the modified layer of the magnesium alloy member, typically the entire surface of the modified layer, and cured after being joined to another member made of any material. If it is resin to perform, it will not specifically limit, Various adhesive resin can be used. In particular,
(1) Hot such as polyolefin (polyethylene (PE), ethylene-vinyl acetate (EVA), etc.), synthetic rubber (polybutadiene (SBS), polyisoprene (SIS), etc.), polyamide, polyester, etc. Melt resin (2) Epoxy resin (3) Urethane resin (4) Natural rubber, styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), ethylene-propylene rubber (EPDM), chloroprene rubber (CR ), Butyl rubber (IIR), synthetic rubber such as butadiene rubber (BR), etc. (5) acrylic resin such as second generation acrylic (SGA) (6) urea resin (7) melamine resin (8) phenol resin ( 9) A silicone resin containing a modified silicone can be used.

As a method of applying such an adhesive resin onto the modified layer of the magnesium alloy member, it can be applied directly with a brush or brush, or impregnated into a cloth in advance, or spray, blade coater, air knife coater. There are a coating method using a coating apparatus such as a roll coater, bar coater, gravure coater, flow coater, curtain coater, and a coating method using dipping, a coating gun, etc., but it is not limited to these.
Moreover, after apply | coating adhesive resin and joining with a counterpart member, in order to accelerate | stimulate hardening of adhesive resin, heat processing and a humidification process can be implemented suitably as needed. In particular, when an epoxy resin, a urethane resin, or a silicone resin is used, it is preferable to promote curing at a temperature of 40 ° C. to 150 ° C. and a humidity of 30% RH to 100% RH.

  Of the various adhesive resins described above, it is particularly preferable to use at least one selected from the group consisting of acrylic resins, urethane resins, epoxy resins, and silicone resins, thereby providing sufficient workability and fast curability. Durable durability can be realized.

  Examples of the acrylic resin include a thermoplastic acrylic resin, a thermosetting acrylic resin, and a moisture curable acrylic resin. However, the acrylic resin is not particularly limited, and various acrylic resins can be used. Specific examples of the thermoplastic acrylic resin include acrylic acid esters such as methyl methacrylate and ethyl acrylate, and polymers and copolymers of methacrylic acid esters. In this case, the ester group of the esterified product may be an alkyl group such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-hexyl, lauryl, and stearyl. In the case of a copolymer, two or more types of ester groups can be used in combination.

  Specific examples of thermosetting acrylic resins include monomers having functional groups (carboxyl group, hydroxyl group, amino group, methylol group, epoxy group, etc.) that can form a crosslinked structure in the molecule, such as acrylic acid and methacrylic acid. , Acrylamide, methacrylamide, N-methylol acrylamide, allyl glycidyl ether, glycidyl methacrylate, and the like, and those having no such functional group, for example, styrene and the above-mentioned acrylic acid or methacrylic acid ester group. And a polymer obtained by copolymerizing two or more monomers.

Specific examples of the moisture curable acrylic resin include methyl cyanoacrylate, ethyl cyanoacrylate, propyl cyanoacrylate, and butyl cyanoacrylate.
Among these acrylic resins, a thermosetting acrylic resin or a moisture curable acrylic resin is preferable.

Furthermore, the acrylic resin may contain an additive as necessary. Such additives include:
(1) Antioxidants such as hindered amines, hydroquinones, hindered phenols, sulfur-containing compounds (2) Ultraviolet absorbers such as benzophenones, benzotriazoles, salicylic acid esters, metal complexes, etc. (3) Metal soaps, heavy metal inorganics and organics Weather-resistant stabilizers such as salts and organotin compounds (4) Plasticizers such as phthalate esters, phosphate esters and fatty acid esters (5) Paraffin wax, polymer wax, beeswax, whale wax, low molecular weight polyolefin, etc. Waxes (6) Organic and inorganic fillers such as calcium carbonate, kaolin, talc, mica, bentonite, clay, carbon black, glass balloon, acrylic resin powder, phenol resin powder, ceramic powder, zeolite, titanium oxide (7) Glass fiber, aramid fiber, carbon fiber, Organic and inorganic fibers such as nylon fiber, nylon fiber, polyester fiber, alumina fiber, boron fiber, etc. (8) Antistatic agents (9) Antibacterial agents (10) Dehydrating agents (11) Flame retardants (12) Solvents (13) Pigments (14) perfumes (15) curing accelerators and the like. Two or more of these additives can be used in combination.

Next, the urethane resin is not particularly limited as long as it contains a compound having two or more isocyanate groups in the molecule, and various urethane resins can be used.
Specific examples of the compound having two or more isocyanate groups in the molecule include 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), 4,4′-diphenylmethane diisocyanate (4,4′-MDI), 2,4′-diphenylmethane diisocyanate (2,4′-MDI), 1,4-phenylene diisocyanate, xylylene diisocyanate (XDI), tetramethylxylidene Aromatic diisocyanates such as diisocyanate (TMXDI), tolidine diisocyanate (TODI), 1,5-naphthalene diisocyanate (NDI), hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, nor Aliphatic diisocyanates such as bornane diisocyanate methyl (NBDI), fats such as transcyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), H6-XDI (hydrogenated XDI), H12-MDI (hydrogenated MDI) Examples thereof include cyclic diisocyanates, carbodiimide-modified diisocyanates of the above diisocyanates, or isocyanurate-modified diisocyanates, and one or more of these may be used in combination. Among these, 4,4′-MDI, 2,4′-MDI, HDI, XDI, or those obtained by prepolymerizing these compounds is preferable.

Moreover, as a urethane resin, a polyol compound can be used together as needed in addition to the compound having two or more isocyanate groups in the molecule. The polyol compound is not particularly limited as long as it contains a compound having two or more hydroxyl groups in the molecule.
Specific examples include polyether polyols such as polyethylene glycol (PEG), polypropylene glycol (PPG), and polytetramethylene ether glycol (PTMG), and condensation and lactone polyester polyols. Of these polyol compounds, polyether polyols are preferred.

Furthermore, the urethane resin may contain a catalyst as necessary in addition to the compound having two or more isocyanate groups in the molecule. The catalyst is not particularly limited as long as it accelerates or delays the curing rate of the urethane resin as necessary, and various catalysts can be used.
Specific examples include monoamines such as triethylamine (TEA) and N, N′-dimethylcyclohexylamine (DMEDA), N, N, N ′, N′-tetramethylethylenediamine (TMEDA), N, N, N Diamines such as', N'-tetramethylhexane-1,6-diamine (TMHMDA), N, N, N ′, N ″, N ″ -pentamethyldipropylene-triamine (PMDPTA), tetramethylguanidine (TMG) triamines, triethylenediamine (TEDA), N, N′-dimethylpiperazine (DMP), cyclic amines such as N-methylmorpholine (NMMO), dimethylaminoethanol (DMEA), N-methyl-N Examples include alcohol amines such as'-(2-hydroxyethyl) -piperazine (MHEP). Of these catalysts, triamines and cyclic amines are preferable.

  In addition, the urethane resin may contain an additive as necessary in addition to the compound having two or more isocyanate groups in the molecule. Such additives are the same as those described above, and two or more kinds can be used in combination.

The epoxy resin is not particularly limited as long as it contains an epoxy compound having two or more epoxy groups in the molecule and a curing agent, and various epoxy resins can be used.
Specific examples of such epoxy compounds include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, biphenyl type epoxy resins, and glycidyl ester type epoxies. Examples thereof include resins, alicyclic epoxy resins, and heterocyclic epoxy resins. Bisphenol A type epoxy resins and bisphenol F type epoxy resins are preferable.

  Specific examples of the curing agent include ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), isophoronediamine (IPDA), N-aminoethylpiperazine (N Aliphatic amines such as m-xylenediamine (MXDA), aromatic amines such as metaphenylenediamine (MPDA), diaminodiphenylmethane (DDM), diaminodiphenylsulfone (DDS) , Other amines such as dicyandiamide (DICY) and adipic acid dihydrazide (AADH), modified polyamines such as epoxy compound-added polyamine, Michael added polyamine, and Mannich added polyamine, polyamide amines, Hydrophthalic acid (PA), tetrahydrophthalic anhydride (THPA), hexahydrophthalic anhydride (HHPA), methyltetrahydrophthalic anhydride (MeTHPA), methylhexahydrophthalic anhydride (MeHHPA), methyl nadic anhydride (MNA), Dodecyl succinic anhydride (DDSA), pyromellitic anhydride (PMDA), benzophenone tetracarboxylic anhydride (BTDA), ethylene glycol bis (anhydrotrimate) (TMEG), trimellitic anhydride (TMA), polyazeline acid Examples include anhydrides (PAPA) acid anhydrides, and preferred are aliphatic amines, other amines, modified polyamines, and polyamidoamines.

Moreover, the said epoxy resin may also contain a catalyst as needed other than the compound and hardening | curing agent which have 2 or more of epoxy groups in a molecule | numerator. As such a catalyst, any catalyst can be used without particular limitation as long as it accelerates or delays the curing rate of the epoxy resin as necessary.
Specific examples include 2- (dimethylaminomethyl) phenol (DMP-10), 2,4,6-tris (dimethylaminomethyl) phenol (DMP-30), triethanolamine, tetramethylguanidine, pyridine, Although tertiary amines such as picoline, piperidine, pyrrolidine, 1,8-diazabiscyclo (5,4,0) undecene-1 (DBU) and the like can be mentioned, DMP-10 and DMP-30 can be preferably used.

  Furthermore, the said epoxy resin may also contain an additive as needed other than the compound and hardening | curing agent which have 2 or more of epoxy groups in a molecule | numerator. As this additive, it is the same as that of the above-mentioned additive, and can use 2 or more types together.

The silicone resin includes a thermosetting silicone resin and a moisture curable silicone resin, but is not particularly limited, and various silicone resins can be used.
Specific examples of the thermosetting silicone resin include a composition mainly composed of an organopolysiloxane having a vinyl group and an organohydropolysiloxane having an Si-H group, and a platinum complex as a catalyst. . Specific examples of the moisture curable silicone resin include dealcohol-free silicone resin, deoxime-type silicone resin, deacetate-type silicone resin, deamidation-type silicone resin, and deacetone-type silicone resin. Of these silicone resins, moisture curable silicone resins are preferred.

  The silicone resin may contain an additive as necessary. As this additive, it is the same as that of the above-mentioned additive, and can also use 2 or more types together.

  The method of using these adhesive resins is not particularly limited as long as it is a method in which the adhesive resin is applied to at least a part of the metal surface, bonded to a member made of any material, and then cured. However, from the viewpoint of durable adhesiveness, after applying the curable resin solution obtained by diluting the curable resin with a solvent in advance to at least a part of the modified surface, volatilizing and drying the solvent, and then using an application gun A method of applying an adhesive resin and bonding and curing the mating member is preferable. If necessary, the adhesive resin solution may be applied and dried in advance on the joint surface of the mating member as well.

In the joined body formed by adhering the magnesium alloy member of the present invention, Al is enriched on the surface of the modified layer, hard-to-adhere magnesium oxide is reduced, and functional groups contained in the adhesive resin (adhesive) As a result, a covalent bond or a hydrogen bond between Al and Al is easily formed, and excellent adhesiveness is exhibited over a long period of time.
In particular, when the double hydroxide as described above is formed on the surface of the modified layer, the adhesive strength is such as the double hydroxide and the acrylic group, epoxy group, isocyanate group, hydroxyl group, etc. contained in the adhesive resin. This is thought to be the sum of physical adhesion forces generated by the formation of chemical bonds such as covalent bonds and hydrogen bonds with functional groups, and the presence of crystal water and adsorbed water. Therefore, extremely excellent durable adhesiveness is exhibited with respect to conventional chemical conversion treatment and blast treatment.

  In addition, the magnesium alloy member of the present invention can be printed or painted using ink or paint on at least a part of the surface of the modified layer, and is based on the same principle as in the case of bonding (adhesion) described above. Excellent adhesion to paints and inks can be ensured by the physical and physical effects.

  As for the inks and paints described above, as long as they can be applied to at least a part of the surface of the modified layer in the magnesium alloy member of the present invention, typically the entire surface, and exhibit the original functions of the inks and paints, There is no limitation, and various inks and paints can be used.

Specific examples of the ink include offset ink, printing ink, gravure ink, and architectural ink. Specific examples of paints include plastic paints, metal paints, ceramic paints, synthetic leather paints, conductive paints, electrical insulating paints, ultraviolet curable paints, electron beam curable paints, and the like. Can do.
As a method for applying such an ink or paint to the modified surface, a method similar to the method for applying the adhesive resin described above can be employed.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited only to these Examples.

Example 1
Potassium chloride as an inorganic chloride was weighed to 3%, mixed in water, and then stirred with a stirrer to prepare an immersion treatment solution composed of an aqueous potassium chloride solution.
A magnesium alloy plate (AS21X: 25 × 50 × 3 mm) containing 2% Al and 1% Si was immersed in this treatment solution, left for 1 minute, then the surface was washed with water, and then 200 It was dried in an oven maintained at 2 ° C. for 2 hours to obtain a magnesium alloy member of this example. In this example, in order to confirm the influence of the Al content and the double hydroxide on the surface of the modified layer, the immersion time in the aqueous potassium chloride solution was made relatively short to expose the surface of Al. In addition, the crystal water is removed by heating after the treatment to remove the double hydroxide.

  And by the method shown below, the surface state of the modified layer formed on the surface (ratio of the Al content of the modified layer surface to the Al content of the alloy raw material portion, presence or absence of formation of double hydroxide), Initial adhesiveness and durable adhesiveness were evaluated respectively. The results are shown in Table 1.

<Evaluation method>
<Surface condition>
In order to confirm the Al content of the magnesium alloy raw material portion, first, the surface of the magnesium alloy plate before the dipping treatment was polished in a certain direction for 1 minute using sandpaper having a roughness of 320, and then air blow. The foreign matter adhering to the surface was blown off and left for about 5 to 10 minutes. Then, using an X-ray photoelectron spectrometer (JPS-9200, manufactured by JEOL), from the binding energy value (chemical shift) of each metal atom, the bonding state of the metal atom is confirmed, and based on these information, The Al content (mol%) was measured and used as the Al content in the original part.
As a method for confirming the Al content on the surface of the modified layer formed on the magnesium alloy, the Al content (mol%) on the treated surface of the magnesium alloy member after the immersion treatment is similarly measured by the X-ray photoelectron spectrometer. did. And the ratio of Al content with respect to the raw material part calculated | required previously was computed.

  As a method for confirming double hydroxide on the surface of the modified layer, absorption of each compound present on the treated surface of the magnesium alloy member after the immersion treatment is performed using Fourier transform infrared spectroscopic analysis (FT-) IR). From the peak value, the bonding state of the metal atoms was confirmed. Based on these information, the bonding state of Mg and Al elements on the surface of the modified layer was determined.

<Initial adhesiveness>
As shown in FIG. 1, a silicone-based adhesive 2 (TB1217H, manufactured by Three Bond Co., Ltd.) is applied to a region 1b of an end 10 mm of the treated surface in the magnesium alloy member 1 having the modified layer 1a formed on the surface by the above. ) Was applied. Next, as shown in FIG. 2, the surface end of an aluminum alloy plate 3 (ADC12: 25 × 125 × 3 mm) as another member was bonded and cured at room temperature for 168 hours to obtain an adhesion test piece. In addition, as the application amount of the adhesive, the thickness of the cured adhesive resin layer 2 was set to 2 mm.
And the tensile shear test was done using such a test piece. In the tensile shear test, an autograph (AG-I 20 kN, manufactured by Shimadzu Corporation) was used, and the shear strength was measured under a tensile speed of 50 mm / min. After the test, the ratio of the area where the adhesive was cohesive to the coated area of the adhesive was visually determined to obtain the cohesive failure rate.

<Durable adhesiveness>
After preparing an adhesion test piece by the same method as the above-mentioned initial adhesiveness evaluation, it was left in engine oil 5W-30 (SM Strong Save X) temperature-controlled in advance at 150 ° C. for 168 hours, and further at room temperature for 24 hours. After curing, the same tensile shear test was performed.

(Example 2)
A magnesium alloy member of this example was obtained by repeating the same operation as in Example 1 except that the immersion treatment time in the above Example 1 was 5 minutes.
Various evaluation tests were performed in the same manner as described above. The results are also shown in Table 1.

(Example 3)
A magnesium alloy member of this example was obtained by repeating the same operation as in Example 2 except that the drying treatment at 200 ° C. after the immersion treatment was omitted.
Various evaluation tests were performed in the same manner as described above, and the results are also shown in Table 1.

Example 4
A magnesium alloy member of this example is obtained by repeating the same operation as in Example 3 except that the magnesium alloy plate is a magnesium alloy plate (AZ31) containing 3% Al and 1% Zn. It was.
Various evaluation tests were performed in the same manner as described above, and the results are also shown in Table 1.

(Example 5)
A magnesium alloy member of this example was obtained by repeating the same operation as in Example 3 except that the magnesium alloy plate was a magnesium alloy plate (AZ91) containing 9% Al and 1% Zn. .
And about the said member, various evaluation tests are implemented in the same way as the above, and the result is combined with Table 1, and is shown.

(Example 6)
A magnesium alloy member of this example was obtained by repeating the same operation as in Example 3 except that the magnesium alloy plate was a magnesium alloy plate (MRI153) containing 8% Al and 1% Ca. .
And about the said alloy member, various evaluation tests were implemented in the same way as the above. The results are also shown in Table 1.

(Comparative Example 1)
Without polishing the surface of the magnesium alloy plate (AS21X) used in Examples 1 to 3 by the above immersion treatment, the metal surface was polished in a certain direction for 1 minute using a sandpaper having a roughness of 320, Air blow was applied and left for about 5 to 10 minutes to obtain a magnesium alloy member of this example.
And various evaluation tests were implemented in the same manner as described above for the untreated member. The results are also shown in Table 1.

(Comparative Example 2)
A magnesium alloy member of this example was obtained by repeating the same operation as in Comparative Example 1 except that the magnesium alloy plate was made of AZ31 (3% Al, 1% Zn).
Various evaluation tests were performed in the same manner as described above, and the results are also shown in Table 1.

(Comparative Example 3)
A magnesium alloy member of this example was obtained by repeating the same operation as in Comparative Example 1 except that the magnesium alloy plate was made of AZ91 (9% Al, 1% Zn).
Various evaluation tests were performed in the same manner as described above, and the results are also shown in Table 1.

(Comparative Example 4)
A magnesium alloy member of this example was obtained by repeating the same operation as in Comparative Example 1 except that the magnesium alloy plate was made of MRI153 (8% Al, 1% Ca).
Various evaluation tests were performed in the same manner as described above, and the results are also shown in Table 1.

(Comparative Example 5)
A magnesium alloy member of this example was obtained by repeating the same operation as in Comparative Example 1 except that a pure magnesium plate was used as the magnesium alloy plate.
Various evaluation tests were performed in the same manner as described above, and the results are also shown in Table 1.

As shown in Table 1, in the adhesion test piece using the magnesium alloy member according to the embodiment of the present invention having a modified layer having a surface Al content higher than the Al content of the primary part, excellent initial adhesion And durable adhesiveness were confirmed.
In particular, in the magnesium alloy members according to Examples 3 to 6 in which the modified layer containing the double hydroxide is formed on the surface, compared to Examples 1 and 2 in which such double hydroxide is removed, It showed excellent performance, and it was confirmed that having such a modified layer exhibits better adhesion.

  On the other hand, in the magnesium alloy not subjected to the immersion treatment in the aqueous potassium chloride solution, even if Al is contained, the Al content on the surface is not enriched, so the adhesive strength is increased. Inferiority was confirmed.

DESCRIPTION OF SYMBOLS 1 Magnesium alloy member 1a Modified layer 2 Adhesive (adhesive resin layer)
3 Aluminum alloy plate (other members)

Claims (9)

  A magnesium alloy member comprising a magnesium alloy containing Al, having a modified layer on the surface thereof, and an Al content on the surface of the modified layer being higher than that of the original part.   2. The magnesium alloy member according to claim 1, wherein the Al content of the raw material portion is 2% or more by mass ratio.   The magnesium alloy member according to claim 1 or 2, wherein the Al content on the surface of the modified layer is 1.5% or more of the original part.   The magnesium alloy member according to any one of claims 1 to 3, wherein a double hydroxide containing Al and Mg is formed on a surface of the modified layer.   The magnesium alloy member according to any one of claims 1 to 4, wherein the surface of the modified layer is bonded to another member via an adhesive resin layer.   6. The magnesium alloy member according to claim 5, wherein the adhesive resin layer is made of at least one resin selected from the group consisting of acrylic resin, urethane resin, epoxy resin and silicone resin.   The magnesium alloy member according to any one of claims 1 to 4, wherein a coating film is formed on a surface of the modified layer.   The magnesium alloy member according to any one of claims 1 to 7, wherein the modified layer is formed by an immersion treatment in an aqueous solution containing an inorganic chloride.   The magnesium alloy member according to claim 8, wherein the inorganic chloride is a metal chloride.

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